One of the most stringent blocks in a high-power transmitter is the power amplifier. To obtain the high power (wattage) required many transmitters use vacuum tube technology, otherwise known as travelling wave tube amplifiers (TWTs). Microwave tube amplifiers can generate high power, but have a high mean time to failure as well as narrow bandwidth.
Instead of using vacuum tube technology, solid-state technology has proven to be more reliable and broader in bandwidth. However, most solid-state-technologies are not capable of generating the high power required for various applications. For example, a TWT amplifier might be able to support 100 Watts of power in the Ku-Band (12-18 GHz), whereas a state-of-the-art Gallium Nitride (GaN) solid state amplifier might only be able to support 20 Watts. However, if five GaN amplifiers are used in parallel, the power rating may be increased to support 100 Watts. For this reason, low-loss, high-power combining/dividing technologies are required to “gang-up” numerous solid-state amplifiers to support the high power requirements.
In the microwave/millimeter-wave regime, combiner/divider techniques utilizing printed circuit board (PCB) transmission lines are not preferable because of the high losses. Waveguide transmission lines are preferable instead, since they can handle high power and have very low loss. However, currently available waveguide/coaxial radial combiners/dividers lack wideband operation. Accordingly, a need exists for a wideband radial combiner that efficiently combines multiple solid state amplifiers to provide high power output.